On this day in 1997, Scientists in Scotland announced the birth of the world's first successfully cloned mammal, Dolly the sheep.
Dolly, who was created at the Roslin Institute in Edinburgh, was actually born on 5 July 1996 although her arrival has only just been revealed.
Dolly is the first mammal to have been successfully cloned from an adult cell. Previous clonings have been from embryo cells.
The sheep's birth has been heralded as one of the most significant scientific breakthroughs of the decade although it is likely to spark ethical controversy.
Scientists in Scotland cloned a ewe by inserting DNA from a single sheep cell into an egg and implanted it in a surrogate mother.
They now have a healthy seven-month-old sheep - Dolly - who is an exact genetic duplicate of the animal from which the single cell was taken.
DNA tests have revealed that Dolly is identical to the ewe who donated the udder cell and is unrelated to the surrogate mother.
Embryologist Dr Ian Wilmut, from the Roslin Institute, said: "It will enable us to study genetic diseases for which there is presently no cure and track down the mechanisms that are involved."
The research, published in Nature magazine, follows the Edinburgh team's success in cloning sheep embryos. Last year they produced two identical sheep, which were clones of an original embryo.
The company which has bought the rights to the research, PPL Therapeutics, said Dolly would help to improve understanding of ageing and genetics and lead to the production of cheaper medicines.
US President Bill Clinton has set up a special task force to investigate cloning in order to examine the legal and ethical implications.
The cloning of Dolly the sheep raised moral dilemmas amid fears that the technique could be used to clone humans.
Dr Ian Wilmut, who led the team of Scottish scientists who were behind the birth of Dolly, described human cloning as both "repugnant" and illegal.
The news about Dolly's birth enraged animal rights activists and the Church of Scotland said while it was "fascinating" research work, it had reservations.
Dr Wilmut also revealed the thinking behind the sheep's name: "Dolly is derived from a mammary gland cell and we couldn't think of a more impressive pair of glands than Dolly Parton's."
A decision was taken in 2003 to put down Dolly after a veterinary examination showed she had a progressive lung disease. Her preserved body went on display at the National Museum of Scotland in Edinburgh.
